Spanish - its an almost universal second language in the Bronx. In the courthouse, it's constant. When asked whether their primary language was English or Spanish, many of our clients answer: "Both." So we decided to add an option for English/Spanish Bilingual. In our intake interview we ask our clients what language they primarily speak in the home (although sometimes I re-word this question a little bit, because a significant number of our clients may be living on the street or in a shelter). Our database has a selection of about 20 representative languages. While it's fairly comprehensive, it's clear it wasn't written with the Bronx in mind! It contains languages I've never encountered in 2.5 years worth of interviews, such as Yiddish, Jordanian, and Japanese, but it doesn't really capture the language diversity I encounter: heavy Jamaican Patois and different creoles, French from West Africa, Guyanese Hindi, Albanian, Chinese.
The idea for writing this post sprang into my head when I found this fascinating website (via Metafilter): the International Dialects of English Archive, IDEA All recordings are in English, are of native speakers, and you will find both English language dialects and English spoken in the accents of other languages.